The present invention relates to miniature or sub-fractional horsepower permanent magnet synchronous motors of the type typically employed for operating timing mechanisms and time-based electromechanical programmers. The invention relates particularly to such motors employed for operating the advance mechanisms and programmers utilized in household appliances such as washing machines, clothes driers, and dishwashers.
Such motors are also particularly suitable for powering small cooling fans employed for cooling electronic circuitry and equipment where compactness is required in order to locate the fan directly adjacent the particular electronic components such as those mounted on a circuit board. Other applications for such motors include aspirators associated with temperature sensing in a flow of air and liquid pumps, particularly for highly competitive mass production applications such as in automotive sensors and controls.
Heretofore, miniature synchronous motors have employed a coil wound around a bobbin which is assembled with a rotor and encased in a shell or housing which forms a part of the magnetic flux loop about the coil, and which may also contain the speed-reducing gear train for power coupling the motor to the mechanism to be driven. The known techniques for mounting the motor coil in the ferromagnetic stator pieces or housing have resulted in relatively expensive assembly operations and complex procedures for attaching the coil leads to connector terminals provided on the stator or housing. Therefore, it has long been desired to provide an improved design for a miniature synchronous timing motor having a minimum volume, and which results in reduced manufacturing costs, yet is simple and reliable.